Commonly today, display data may be presented on a display for illustrating various types of information to a user. For instance, maps, photographs, videos, and/or other graphic data is commonly presented via a display of an electronic device. Users often desire to navigate through the display data, such as by panning, zooming in, and/or zooming out through the display data. As an example, when viewing a map being displayed, a user may desire to pan through the map to find a location of interest (e.g., a particular portion of a city), and then the user may desire to zoom in on the location of interest to view greater detail about such location (e.g., street names, etc. in the particular portion of the city). Challenges arise in enabling a user to navigate efficiently through the display data, particularly in a manner that aids the user in not becoming “lost” within the display data. That is, it becomes desirable to aid a user in navigating through display data in a manner that the user can understand where within the display data he/she is navigating.
Particular navigation challenges are presented when displays are small and/or when the user input available for controlling the navigation is limited. Many devices provide small displays and/or limited user input for controlling navigation. For instance, electronic devices such as mobile phones, personal digital assistants (PDAs), and the like, often have small screen displays wherein a user may desire to navigate through information, such a map, a large spread sheet, a large graphic, or the like, that exceeds the display area of the screen. In such case, only a small portion of the information may be presented at a given time on the small screen display, and it becomes desirable to assist a user in navigating through the information while maintaining a sense of how the information fits together. On desktop computers, the screen is typically large enough to display a section of a map that is large enough to make out details, such as street names, terrain features, and the like, as well as show a sufficient amount of area around a specific area of interest. With the larger screen and a pointing device, the user has many options to effectively interact with the map. To zoom into a specific area, a user can continually select that area with a zoom tool. The user may also get an area of interest to show up in the center of the device display by clicking on that part of the map while in a “click to re-center” mode. Alternatively, a user may select and drag that part of the map to bring it into the center of the display screen.
Having much smaller screens, mobile phone and PDA users will typically need to zoom closer into a map, a graphic, spreadsheet, or the like, to make out details such as street names, illustration details, cell entries, and the like. It generally takes many steps of panning and zooming to get a particular area of interest to show up at the desired size and position on the display screen. At such a detailed view, the user may not easily be able to look at the area surrounding the area of interest represented on the screen without executing many additional panning and zooming steps, which may cause the user to lose context of the area of interest the user initially desired to see. Overall, instead of feeling like holding a portable foldable map in your hands, the resulting experience is more like interacting with a wall-sized map by looking through a cardboard tube and then walking closer or farther from the wall to zoom in and out. Further, many such electronic devices provide only limited user input ability for controlling the navigation. For instance, a mobile telephone may only provide a 5-way input interface that includes 4 directional inputs (e.g., left, right, up, and down buttons) and 1 selection input (e.g., an OK button). This may further increase the user's difficulty in navigating through display data.
In the mobile map application space, map and direction providers present a requested map to a user on a mobile phone or PDA connected to the Internet. Examples of such mobile mapping and directions applications are Google, Inc.'s GOOGLE™ Maps Mobile (GMM), and Verizon Wireless' VZ NAVIGATORSM. In GMM, the user downloads the GMM software to the particular mobile phone or PDA, which then interacts via the Internet or wireless provider system with the map databases operated by Google, Inc. In response to a request from a user, a portion of the map is generally downloaded to the user's device, with the particular area of interest being centered on the small screen of the device. The GMM application provides a user interface (UI) for the user to interact with the map by panning in four directions, zooming in, zooming out, re-centering, and the like. When panning around the map, only small movements are made in any of the selected directions. More of the map is downloaded to accommodate this panning. However, the limitation of small panning movements makes it difficult to quickly look at the area surrounding the current view if the user desires to get a sense of where the current view is in relation to the larger area of the map.
While the small panning steps make such localized panning more difficult, larger palming steps would not necessarily solve this difficulty in a desirable manner. If the UI simply panned further with each key press, the user would tend to lose track of where they are on the map if it moves too far from its previous position. Therefore, when the user selects to pan in any particular direction, only a very small amount of distance is moved, in order to preserve the user's context in interacting with the subject map. However, even with limiting the amount of movement between each series of pans, the user's experience may be tenuous because there is also nothing that conveys what is happening to the user as the user operates the interface controls.
In one feature of GMM, the zoom feature, GMM inserts a rectangle over the area in the middle of the screen that either is to be zoomed into or indicates the area from which the display was zoomed out from. The rectangle loosely frames the area on the screen that has or is to be expanded or zoomed into. However, the rectangle is only placed onto the display screen after the user indicates to perform one of the zoom directions. Thus, there is no indication to the user in advance of activating the feature as to what may happen when it is activated.